I have experience on quite a lot of occassions that some AI just bluntly refuse to take orders, specifically the snipers.
In many missions I have played/made the sniper at some point normally fairly early on into the mission will holster his rifle and pull out his pistol, then generally after that point he is rendered almost useless as he no longers regroups, moves to next waypoint, he just sits there etc.
I have noticed this with other units on occassion, usually when they run out of ammo. But snipers are a specific problem. I now tend to omit them from my missions for that reason.
I have on certain missions triggers that are activated by the whole group being in a vehicle or a zone etc, and this issue cocks it right up.
Due to their lack of disipline I end up taking the extreme action of shooting them once they do this, which makes me the bad guy
If a solution to this issue could be found I could again be the